Response surface analysis of extraction technology for flavonoids from Radix puerariae

In order to make full use of Radix puerariae resource and exploit its active components. The optimal extraction technology for flavonoids from Radix puerariae was studied by means of orthogonal rotational combination design. Flavonoids was extracted by ethanol as solvent from Radix puerariae. The effects of the factors, including ratio of solid to liquid, extraction temperature, ethanol concentration and extraction time, on the yield rate were investigated. On the basis of single factor experiments, a central composite involving four variables at four levels was employed, the optimal values of these variables were determined by response surface analysis. The results showed that regression equation fitted well with the experimental data, the optimum extraction conditions were: the ratio of solid to liquid 1:27.70, extraction temperature 80.86 ℃, ethanol concentration 61.24%, extraction time 1.97 h。 In this condition, the predicted value of the maximal yield of flavonoids is 6.60% while the effective value is 6.64%.